"Her outlook was 'Nothing is impossible,' " says Cate. "She never gave up hope even in her last week of life; she never gave up hope that a cure could be out there and that she could beat this."

Talking to Mitchell at the Susan G. Komen 3-Day Walk for the Cure, Edwards also announced the creation of the Elizabeth Edwards Foundation, which she called "a perfect reflection" of her mother. The organization will support high school students who have limited resources but "great potential," according to its website.

"Big choices that I make … little choices that I make, sort of everything I do, I hear her voice," says Cate, "the same way I did when she was alive."